24: Motor Tracts

Question 1

Primary motor cortex

Answer 1

Precise and individual movements of digits and extremities

Question 2

Premotor cortex

Answer 2

Ideation and programming of movement patterns

Question 3

Supplementary motor cortex

Answer 3

Influences limb musculature and movement

Question 4

UMNs vs LMNs

Answer 4

UMNs: terminate on another neuron
LMNs: terminate on a muscle cell

Question 5

UMN paralysis

Answer 5

Spastic paralysis, hypertonia, hyperreflexia, Babinski sign, clonus, rigidity

Question 6

LMN lesion

Answer 6

Flaccid paralysis, areflexia, atonia, atrophy, fasciculations

Question 7

Two types of LMNs and what they innervate

Answer 7

Alpha MNs: innervate extrafusal skeletal muscle

Gamma MNs: innervate intrafusal fibers

Question 8

LMN pools

Answer 8

Group of highly inter connected interneurons in intermediate gray matter

Question 9

Lesion of the CST

Answer 9

Contralateral spastic hemiplegia or hemiparalysis

Question 10

Lesion of the LCST

Answer 10

Ipsilateral paralysis or paresis of distal limb musculature below level of lesion

Question 11

Lesion of ACST

Answer 11

Minimal clinical effect

Question 12

Blood supply to the CST

Answer 12

Parmedian branches of the basilar A

Question 13

Lesion above and below decussation in the corticobulbar tract

Answer 13

Above decussation: contralateral CN palsies (ex: supranuclear facial palsy)
Below decussation: ipsilateral CN palsies

Question 14

How to generally test to see if the corticobulbar tract is intact?

Answer 14

Performing a typical neuro exam of the CNs

Question 15

If multiple abnormal CN findings on exam…

Answer 15

Lesion most likely at superior CN on side of deficits

Question 16

What causes acute anterior poliomyelitis?

Answer 16

Inflammation of MNs in anterior horn, neuron death, astrocytic gliomas form

Question 17

S/S of acute anterior poliomyelitis

Answer 17

fever, HA, N/V, neck stiffness, pain in back and limbs (like any other acute viral meningitis)

Question 18

What does ALS stand for?

Answer 18

Amyotropic lateral sclerosis

Question 19

ALS: structures involved

Answer 19

LMNs and UMNs

Question 20

S/S ALS

Answer 20

Paresis and atrophy of hands -> arms -> shoulders; dysarthria, dysphagia, paresis of tongue, spastic paralysis, hyperreflexia, Babinski sign

Question 21

What causes supranuclear facial paralysis?

Answer 21

Unilateral lesion of corticobulbar fibers above level of facial nucleus

Question 22

Two parts of the facial motor nucleus and what they receive fibers from

Answer 22

Anterior part: receives corticobulbar fibers

Posterior part: receives fibers from both hemispheres

Question 23

What is innervated by the anterior and posterior parts of the facial motor nucleus?

Answer 23

Anterior part: muscles of lower quadrant of face

Posterior part: muscles of upper quadrant of face

Question 24

S/S supranuclear facial paralysis

Answer 24

Palsy of contralateral mimetic muscles on lower quadrant of face

Question 25

Bell’s palsy

Answer 25

Ipsilateral paralysis of mimetic muscles

Question 26

What cases Bell’s palsy

Answer 26

Central lesion of facial nerve

Question 27

What causes a Lenticulostriate infarct?

Answer 27

Ischemia in territory of ICA or MCA

Question 28

S/S Lenticulostriate infarct

Answer 28

Motor and/or sensory deficits, cognitive dysfunction

Question 29

CN 3 motor component

Answer 29

Extrinsic eye muscles (besides SO, LR), levator palpebrae superioris, constrictor pupillae, ciliary muscles of lens

Question 30

CN 4 motor component

Answer 30

SO

Question 31

CN 5 motor component

Answer 31

Muscles of mastication, tensor tympani, tensor veli palatini, mylohyoid, anterior belly digastric

Question 32

CN 6 motor component

Answer 32

LR

Question 33

CN 7 motor component

Answer 33

Mimetics, stapedius

Question 34

CN 9 motor component

Answer 34

Stylopharyngeus

Question 35

CN 10 motor component

Answer 35

Striated and smooth muscles of pharynx/larynx, smooth muscles in thorax and abdomen

Question 36

CN 11 motor component

Answer 36

SCM, trapezius

Question 37

CN 12 motor component

Answer 37

Intrinsic and extrinsic tongue musculature

Question 38

Apraxia

Answer 38

Inability to properly perform complex learned motor acts

Question 39

Agnosia

Answer 39

E: right-left disorientation

Question 40

Areflexia

Answer 40

Loss of efferent component of reflex arc

Question 41

Atonia

Answer 41

Absence of muscle tone

Question 42

Fasciculations

Answer 42

Twitching

Question 43

Dystonia

Answer 43

Uncontrolled muscle contractions - repetitive movements